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Introduction to the Human Body
Overview of Anatomy and Physiology Anatomy: scientific study of the body's structures *''Gross anatomy (macroscopic anatomy):'' study of the larger structures of the body, those visible without the aid of magnification *''Microscopic anatomy:'' study of structures that can be observed only with the use of a microscope or other magnification devices *''Regional anatomy:'' study of the interrelationships of all the structures in a specific body region *''Systemic anatomy:'' study of the structures that make up a discrete body system Physiology: scientific study of the chemistry and physics of the strucutres of the body and the ways in which they work together to support the functions of life Homeostasis: state of steady internal conditions maintained by living things Structural Organization of the Human Body Cell: smallest independently functioning unit of a living organism *''Cytoplasm:'' water-based cellular fluid *''Organelle:'' variety of tiny functioning units within a cell Tissue: group of many similar cells that work together to perform a specific function Organ: anatomically distinct structure of the body composed of two or more tissue types Organ system: group of organs that work together to perform major functions or meet physiological needs of the body *''Integumentary system:'' **encloses internal body structures **sites of many sensory receptors *''Skeletal system:'' **supports the body **enables movement (with muscular system) *''Muscular system:'' **enables movement (with skeletal system) **helps maintain body temperature *''Nervous system:'' **detects and processes sensory information **activates bodily responses *''Endocrine system:'' **secretes hormones **regulates bodily processes *''Cardiovascular system:'' **delivers oxygen and nutrients to tissues **equalizes temperature in the body *''Lymphatic system:'' **''returns fluid to blood **defends against pathogens *''Respiratory system: **''removes carbon dioxide from the body **delivers oxygen to blood *''Digestive system: **processes food for use by the body **removes wastes from undigested food *''Urinary system:'' **controls water balance in the body **removes wastes from blood and excretes them *''Male reproductive system:'' **produces sex hormones and gametes **delivers gametes to female *''Female reproductive system:'' **produces sex hormones and gametes **supports embryo/fetus until birth **produces milk for infant Organism: living being that has a cellular structure and that can independently perform all physiologic functions necessary for life Functions of Human Life Metabolism: sum of all anabolic and catabolic reactions that take place in the body *''Anabolism:'' process whereby smaller, simpler molecules are combined into larger, more complex substances **utilizes energy *''Catabolism:'' process by which larger, more complex substances are broken down into smaller, simpler molcules **releases energy *''Adenosine triphosphate (ATP):'' chemical compound used to store and release energy Responsiveness: ability of an organism to adjust to changes in its internal and external environments Development: all of the changes the body goes through in life *''Differentiation:'' unspecialized cells become specialized in structure and function to perform certain tasks in the body Growth: increase in body size Reproduction: formation of a new organism from parent organisms Requirements for Human Life Oxygen *brain cells are especially sensitive to lack of oxygen due to their requirement for a high and steady production of ATP *brain damage likely within 5 minutes without oxygen **death likely within 10 minutes Nutrient: substance in foods and beverages that is essential to human survival *''Water'' **can only survive a few days without water **makes up 70% of an adult's body mass **helps regulate internal temperature and cushions, protects, and lubricates joints and other body structures *''Macronutrients'' **energy-yielding nutrients are primarily carbohydrates and lipids **proteins mainly supply the amino acids **can survive without energy-yielding nutrients for several weeks *''Micronutrients'' **vitamins and minerals **some can be stored, thus can survive without them for a few days or weeks **other cannot be stored, so they must be consumed every day or two Temperature *chemical reactions in the body can only take place just above/below 37 degrees Celsius *sweating is body's response to heat **adequate water intake required when sweating **less effective in humid environments since sweat cannot evaporate *shivering is body's response to cold *increased breakdown of stored energy **when energy reserve is depleted, core temperature significantly drops and RBC's lose ability to give up oxygen **causes confusion, lethargy, loss of consciousness, death *body reduces blood flow to extremities **can lead to frostbite and gangrene Pressure: force exerted by a substance that is in contact with another substance *altitude sickness results from less pressure at high altitudes, reducing exchange of gases **causes dyspnea, confusion, headache, lethargy, and nausea Homeostasis Set point: physiological value around which the normal range fluctuates Normal range: restricted set of values that is optimally healthful and stable Negative feedback: mechanism that reverses a deviation from the set point *''Sensor (receptor):'' component of a feedback system that monitors a physiological value *''Control center:'' component in a feedback system that compares the value to the normal range *''Effector:'' component in a feedback system that causes a change to reverse the situation and return the value to the normal range *examples include blood glucose and sweating Positive feedback: mechanism that intensifies a change in the body's physiological condition rather than reversing it *example includes childbirth and penetrating wounds Anatomical Terminology Anatomical position: body standing upright with the feet at shoulder width and parallel, toes forward; upper limbs are held out to each side, and the palms of the hands face forward Prone: face-down orientation Supine: face-up orientation Directional terms *''Anterior (ventral):'' front or direction toward the front of the body *''Posterior (dorsal):'' back or direction toward the back of the body *''Superior (cranial):'' above or higher than another part of the body *''Inferior (caudal): below or lower than another part of the body *Lateral:'' direction toward the side of the body *''Medial:'' direction toward the middle of the body *''Proximal:'' position on a limb that is nearer to the point of attachment or the trunk of the body *''Distal:'' position on a limb that is further from the point of attachment or the trunk of the body *''Superficial: closer to the surface of the body *Deep:'' farther from the surface of the body Body planes *''Sagittal plane:'' plane that divides the body or an organ vertically into right and left sides **''Midsagittal (median) plane:'' plane that runs directly down the middle of the body **''Parasagittal (longitudinal) plane:'' plane that divides the body into unequal left and right sides *''Frontal (coronal) plane:'' plane that divides the body or an organ into a front and rear portion *''Transverse plane (cross section):'' plane that divides the body or an organ horizontally into upper and lower portions Body cavities *''Dorsal (posterior) cavity:'' contains the brain and spinal cord **''Cranial cavity:'' contains the brain **''Vertebral (spinal) cavity:'' contains the spinal cord *''Ventral (anterior) cavity:'' abdominal and thoracic cavities **''Thoracic cavity:'' superior subdivision ***''Superior mediastinum'' ***''Pleural cavity'' ***''Pericardial cavity'' **''Abdominal cavity:'' abdomen **''Pelvic cavity:'' most inferior part of the abdomen Abdominal regions Abdominal quadrants Membranes *''Serous membrane:'' one of the thin membranes that cover the walls and organs in the thoracic and abdominopelvic cavities **''Parietal layer:'' lines the walls of the body cavity **''Visceral layer:'' lines the organs **''Pleura:'' serous membrane surrounding the lungs **''Pericardium:'' '''serous membrane surrounding the heart **Peritoneum:' serous membrane surrounding organs of the abdominopelvic cavity Medical imaging '''X-ray:' form of high energy EM radiation with a short wavelength capable of penetrating solids and ionizing gases *best used to visualize hard structures *can damage cell and cause cancer Computed tomography (CT): noninvasive imaging technique that uses computers to analyze several cross-sectional X-rays in order to reveal minute details about bodily structures *especially useful for soft tissue scans *exposes patients to a high dose of radiation Magnetic resonance imaging (MRI): noninvasive medical imaging technique based on a phenomenon of nuclear physics in which matter exposed to magnetic fields and radio wavees was found to emit radio signals *malignant tissue gives off different signals *higher costs, patient discomfort Positron emission tomography (PET): medical imaging technique involving the use of radiopharmaceuticals *can illustrate physiologic activity Ultrasonography: imaging technique that uses the transmission of high-frequency sound waves into the body to generate an echo signal that is converted by a computer into a real-time image *least invasive of all techniques Category:Anatomy & Physiology